April 11, 2003

Damaging landslides in the Wasatch Front increased dramatically in the late 1990s and caused over $1 million in damages. The Utah Geological Survey's newest publication, Characteristics, causes, and implications of the 1998 Wasatch Front landslides, examines the relationship between long-term periods of increased precipitation in northern Utah, rising ground-water levels, and decreasing hillside stability, particularly in pre-existing landslide areas.

Hillside modifications for residential development along the Wasatch Front reduce the stability of many pre-existing landslides, particularly where these modifications accelerate the rise in ground-water levels. Following these natural and human-caused changes to hillside stability, a temporary rise in ground-water level during the late winter snowmelt and early spring wet months was locally sufficient to trigger movement in the late 1990s, particularly in 1998.

The publication examines characteristics of damaging landslides, concluding that in many cases, the short duration and very slow rate of movement precludes the easy recognition of movement by homeowners, building officials, and geologists. Included are recommendations for land-use approaches for future hillside development in landslide-hazard areas in the Wasatch Front area. Also included are new approaches for landslide investigations for use by geotechnical engineers and geologists in characterizing hillside stability.

This new release is available at the Natural Resources Map & Bookstore located at 1594 West North Temple, Salt Lake City, (801-537-3320 or 1-888-UTAHMAP; mapstore.utah.gov) at a cost of $8.